Embodiments of the invention relate generally to angiogram analysis, and more specifically, to associating coronary angiography image annotations with SYNTAX scores for assessment of coronary artery disease.
Cardiovascular disease (CVD) results in more death and disability in both males and females in all western societies than any other disease category, accounting for one third of all deaths in the United States in 2007. Half of these deaths are due to coronary artery disease (CAD), which is the process of atherosclerotic narrowing of coronary arteries which are arteries that supply blood and oxygen to the heart muscle. Any occlusion of these arteries can impact heart function leading to effort intolerance with exertion provoked chest symptoms, heart attack, permanent impairment of heart muscle function, and sudden death.
The “gold standard” diagnostic test for CAD is the coronary angiogram. A coronary angiogram involves placing plastic catheters into the arterial system and injecting iodinated contrast solution into the coronary blood flow, to obtain a silhouette of the coronary arterial wall. The angiographic images are typically recorded at 15 or 30 frames a second, providing a motion picture of the flowing blood and contrast mixture to permit the identification of segmental coronary narrowing or blockage attributable to atherosclerotic plaque accumulation along the interior wall of the artery.
Interpretation of coronary angiograms is nearly always performed by visual estimation of the severity of narrowing in the diseased coronary artery, stated in percent of diameter lost in projections that display the narrowing at its worst. Because of the curvilinear cylindrical structure of an artery and the irregular and often eccentric remaining lumen through the diseased segment, several viewpoints are inspected in the effort to estimate the percentage of narrowing.
Abnormal coronary angiographic findings can be treated by medications, or one of two “revascularization” methods to improve blood flow, coronary artery bypass grafting (CABG) or open heart surgery, and percutaneous coronary interventions (PCI) of balloon angioplasty with coronary stent placement. The former is performed by cardiothoracic surgeons in an operating room under general anesthesia, while PCI is performed in the catheter lab often immediately following coronary angiography, and the patient is discharged home within 24 hours and fully active after three days. There are thus major differences in the cost and impact to patients so that decision making between these options cannot be taken lightly and will depend on the accurate assessment of the state of the coronary artery disease.
A scoring system called the SYNTAX score was developed by cardiologists to quantify the severity and extent of CAD and to reduce observer bias in the interpretation of the angiographic findings and assure equal severity of disease in both treatment groups. The score is calculated in response to 12 questions asking a specialist to describe the coronary artery system they see in a coronary angiogram, including questions about coronary dominance, number of lesions, locations of vessels involved, tortuosity, diffuse arteries, etc. The calculation of the SYNTAX score, however, is a time consuming and dependent on operator training and remains subject to visual quantification biases. Currently, the available methods of calculating the SYNTAX score is either through a paper questionnaire or through an online site syntaxscore.com where the questions are interactively displayed. To answer these questions, the coronary angiogram must be loaded from a picture archiving and communication system (PACS) and be simultaneously visible. There is currently no way to associate the imaging data directly with the questionnaire in order to indicate the lesions based on which the questionnaire was answered. As a result of these difficulties, the SYNTAX score, though often mentioned in discussion of treatment decisions, is rarely actually calculated in the process of routine clinical care. Ideally, a fully automated, operator independent and bias free program would quickly generate a SYNTAX-like score to quantify CAD. Such a program would find broad application in clinical care and might fulfill payer interests in pre-authorization for care